Insect swarms near streetlights contain more predators and scavengers

A study by the University of Exeter has found that street lighting has transformed communities of
insects, and affected the balance of different species living
together in urban environments.

A team of researchers, led by Tom Davies of the Environment and
Sustainability Institute, marched to the market town of Helston in
West Cornwall, and placed pitfall traps below and between street
lamps for a number of days and nights.

They collected 1,194 individuals, from 60 different species.
They found that the bugs were attracted to the lights -- total
numbers were more abundant under the lamps -- and they found that
the balance of insects tipped in favour of predatory and scavenging species, over grazers, parasites, and
detritivores.

The results were the same during the day, as well as at night,
which suggests that the effect on communities is ongoing.

The radically-altered insect communities could have a knock-on
effect on the birds and mammals that rely on these bugs for food.
"We need to be aware of how the increase in artificial lighting is
impacting on the delicate ecosystems on which we all rely," says
Davies.

"Our research shows, for the first time, the changes that light
pollution is making to entire communities of invertebrates. We now
need to examine what impact this is having on other communities and
how this may be affecting important ecosystem services, and whether we should change the way we
light urban spaces."

Previous studies have looked at the light pollution's effect on
individual animals. A 2009 study from Bristol University found
that streetlights threatened the survival of bats, as the bright
lights make them easy pickings for flacons and hawks.